3 Kinds of Compression

Compression is an audio tool that reduces the loudness of the loudest parts and increases the loudness of the quietest parts of a passage of audio. It is especially useful for recording voices since they tend to be quite variable in volume. We can go from a whisper to a shout and back again and everything in between very quickly. This can make it hard on the person listening to the recording. they might have to turn it up when it's too quiet and turn it down when it's too loud. So compressing that audio before we send it out to the world makes it easier for those listeners.

Here is an article discussing the use of compression in music. Specifically it talks about 3 kinds of compressor technology that was used in those compressor boxes we used to rely on before the world of software effects.

The idea is that each type can impart a different character to the audio. It can be effective (no pun intended:)) to add variety to your mixes by mixing (ha!) things up using all three different types of compressor in your song. You could use one type on voices, another on different instruments and another still for the entire mix.